You aren't going to make much improvement if you aren't focusing on compound movements.
If you want to build your chest, you should select two of the following exercises:
Barbell Bench Press
Dumbbell Incline Press
Dumbbell Press
Incline Bench Press
These aren't the only ones to pick from, but I think they would be the easiest for a newcomer.
Personally, I would suggest Flat Bench Press, and Incline Press.
Then for arms, you should consider doing 2 or 3 compound movements and maybe throw in 1 set of isolation movements. Isolation movements are movements were you isolate 1 muscle group such as curls.
So for biceps I say do pull-ups or chin-ups. Then maybe throw in some dumbbell hammer curls. Do you realize that the triceps are much bigger and stronger than biceps. If you want arm size, I would recommend doing some compound movements that really blast the triceps like Dips and close grip bench press.
Use the following site to see how to perform exercises if yo uare unsure how to.
ExRx Exercise & Muscle Directory
Read the training stickies to structure a training program. This is extremely important. If you don't, yo uwill miss out on a wealth of information that can help you do amazing things with your training. Once yo uhave read the training stickies, post your program in the training forum, and we will look it over and give sugestions.
http://www.ironmagazineforums.com/training/60738-training-101-a.html
http://www.ironmagazineforums.com/training/60741-designing-training-routines-cowpimp.html
If you only focus on biceps and chest exercises, you probably won't get very far. Thats just my 2 cents worth.
Also check out the diet and nutrition stickies to learn how you should eat so that you make gains. IF your diet isn't spot on, you will probably not make much progress.
As far as which curl type to do, I mix it up. Sometimes I do straight bar curls, and sometimes I do dumbbell hammer curls. I never do both on the same day.